Added value of ultra high field MRI for detection of a cause of epilepsy

Rationale: The prevalence of epilepsy is reported to be between 5 to 8 per 1,000 inhabitants, with a cumulative risk of having epilepsy somewhere during life of 3%. Based on seizure type, at least 61% of these patients are suffering from localisation related epilepsies (Browne, 2000). Many patients still have no lesion visible on the conventional MRI (3-Tesla) as a possible cause for their epilepsy. In children with epilepsy this is about one-third (Reijs, 2007). The study hypothesis is that the use of higher field strength MRI-scanners will improve the detection of (small) structural brain lesions in patients with focal drug-resistant epilepsy, potentially resulting in better seizure outcome after resective epilepsy surgery.

Objective: The primary purpose of this study is to improve detection rate of (small) structural brain lesions by using ultra high field MRI in patients with focal drug-resistant epilepsy. Secondary purposes are:
1. to compare suspected regions of interest (ROI) in the suspected hemisphere in the non- or semi-invasive workup to the contralateral side.
2. to assess associations between suspected regions of interest (ROI) in the non- or semi-invasive workup and ultra high field MRI data.
3. to assess associations between ultra high field MRI abnormalities, histopathology and postoperative seizure outcome.
4. comparison of 2 ultra high field MRI’s in the same patient
Separately, a research protocol is prepared to study 9.4T MRI results of in vivo ROI’s in a selected group of patients and compare this with surgically removed lesions.

Study design: prospective, longitudinal, observational study

Study population: Patients with drug-resistant focal epilepsy undergoing pre-surgical work-up with a negative conventional 3T MRI but with a positive epileptogenic focus localization by means of other non- or semi-invasive modalities (MEG, PET, SPECT, EEG-fMRI, and/or seizure semiology and clinical history).

Intervention (if applicable): all (n =60) patient-participants will receive a 7T MRI-scan, without intravenous contrast administration. In 10 patients, two ultra high field MRI scans (7T and 9.4T), also without intravenous contrast, will be performed on two different days.

Main study parameters/endpoints:
Primary endpoint: the proportion of patients in whom apparent structural brain lesions are detected on ultra high field MRI.
Secondary endpoints:
1. Differences between the ROI as previous determined in the non- or semi-invasive workup, and the contralateral (non-epileptic) side.
2. Association between suspected ROI in the non- or semi-invasive workup and the ultra high field MRI data.
3. Histopathological diagnosis of surgical specimen 
4. Postoperative seizure outcome (Engel/ILAE class)
5. Differences in ultra high field MRI performed in the same patient

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: 
Burden: One visit to the ultra high field-MRI-unit of Scannexus, Maastricht (two visits for 10 patients).
60 Minutes of MRI-acquisition. 
There are no specific risks associated with the used MRI protocols.
There are possible personal patient benefits in this study. If abnormalities are found in epilepsy surgery candidates the information will be passed on to the epilepsy surgery workgroup. The members of this workgroup are aware that at present the obtained information is not validated and therefore should be interpreted with utmost caution.

The use of higher field strength MRI-scanners will improve the detection of (small) structural brain lesions in patients with focal drug-resistant epilepsy, potentially resulting in better seizure outcome after resective epilepsy surgery.

2 years data collection and 1 year follow up in all operated patients (max. 3 years) + 1 year analysis and publication

All patients will undergo an ultra high field MRI-scan of the brain (in 10 patients twice, i.e. both 7T+9.4T).